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  1. /*
  2. ** $Id: lvm.c,v 2.268.1.1 2017/04/19 17:39:34 roberto Exp $
  3. ** Lua virtual machine
  4. ** See Copyright Notice in lua.h
  5. */
  6.  
  7. #define lvm_c
  8. #define LUA_CORE
  9.  
  10. #include "lprefix.h"
  11.  
  12. #include <float.h>
  13. #include <limits.h>
  14. #include <math.h>
  15. #include <stdio.h>
  16. #include <stdlib.h>
  17. #include <string.h>
  18.  
  19. #include "lua.h"
  20.  
  21. #include "ldebug.h"
  22. #include "ldo.h"
  23. #include "lfunc.h"
  24. #include "lgc.h"
  25. #include "lobject.h"
  26. #include "lopcodes.h"
  27. #include "lstate.h"
  28. #include "lstring.h"
  29. #include "ltable.h"
  30. #include "ltm.h"
  31. #include "lvm.h"
  32.  
  33.  
  34. /* limit for table tag-method chains (to avoid loops) */
  35. #define MAXTAGLOOP      2000
  36.  
  37.  
  38.  
  39. /*
  40. ** 'l_intfitsf' checks whether a given integer can be converted to a
  41. ** float without rounding. Used in comparisons. Left undefined if
  42. ** all integers fit in a float precisely.
  43. */
  44. #if !defined(l_intfitsf)
  45.  
  46. /* number of bits in the mantissa of a float */
  47. #define NBM             (l_mathlim(MANT_DIG))
  48.  
  49. /*
  50. ** Check whether some integers may not fit in a float, that is, whether
  51. ** (maxinteger >> NBM) > 0 (that implies (1 << NBM) <= maxinteger).
  52. ** (The shifts are done in parts to avoid shifting by more than the size
  53. ** of an integer. In a worst case, NBM == 113 for long double and
  54. ** sizeof(integer) == 32.)
  55. */
  56. #if ((((LUA_MAXINTEGER >> (NBM / 4)) >> (NBM / 4)) >> (NBM / 4)) \
  57.         >> (NBM - (3 * (NBM / 4))))  >  0
  58.  
  59. #define l_intfitsf(i)  \
  60.   (-((lua_Integer)1 << NBM) <= (i) && (i) <= ((lua_Integer)1 << NBM))
  61.  
  62. #endif
  63.  
  64. #endif
  65.  
  66.  
  67.  
  68. /*
  69. ** Try to convert a value to a float. The float case is already handled
  70. ** by the macro 'tonumber'.
  71. */
  72. int luaV_tonumber_ (const TValue *obj, lua_Number *n) {
  73.   TValue v;
  74.   if (ttisinteger(obj)) {
  75.     *n = cast_num(ivalue(obj));
  76.     return 1;
  77.   }
  78.   else if (cvt2num(obj) &&  /* string convertible to number? */
  79.             luaO_str2num(svalue(obj), &v) == vslen(obj) + 1) {
  80.     *n = nvalue(&v);  /* convert result of 'luaO_str2num' to a float */
  81.     return 1;
  82.   }
  83.   else
  84.     return 0;  /* conversion failed */
  85. }
  86.  
  87.  
  88. /*
  89. ** try to convert a value to an integer, rounding according to 'mode':
  90. ** mode == 0: accepts only integral values
  91. ** mode == 1: takes the floor of the number
  92. ** mode == 2: takes the ceil of the number
  93. */
  94. int luaV_tointeger (const TValue *obj, lua_Integer *p, int mode) {
  95.   TValue v;
  96.  again:
  97.   if (ttisfloat(obj)) {
  98.     lua_Number n = fltvalue(obj);
  99.     lua_Number f = l_floor(n);
  100.     if (n != f) {  /* not an integral value? */
  101.       if (mode == 0) return 0;  /* fails if mode demands integral value */
  102.       else if (mode > 1)  /* needs ceil? */
  103.         f += 1;  /* convert floor to ceil (remember: n != f) */
  104.     }
  105.     return lua_numbertointeger(f, p);
  106.   }
  107.   else if (ttisinteger(obj)) {
  108.     *p = ivalue(obj);
  109.     return 1;
  110.   }
  111.   else if (cvt2num(obj) &&
  112.             luaO_str2num(svalue(obj), &v) == vslen(obj) + 1) {
  113.     obj = &v;
  114.     goto again;  /* convert result from 'luaO_str2num' to an integer */
  115.   }
  116.   return 0;  /* conversion failed */
  117. }
  118.  
  119.  
  120. /*
  121. ** Try to convert a 'for' limit to an integer, preserving the
  122. ** semantics of the loop.
  123. ** (The following explanation assumes a non-negative step; it is valid
  124. ** for negative steps mutatis mutandis.)
  125. ** If the limit can be converted to an integer, rounding down, that is
  126. ** it.
  127. ** Otherwise, check whether the limit can be converted to a number.  If
  128. ** the number is too large, it is OK to set the limit as LUA_MAXINTEGER,
  129. ** which means no limit.  If the number is too negative, the loop
  130. ** should not run, because any initial integer value is larger than the
  131. ** limit. So, it sets the limit to LUA_MININTEGER. 'stopnow' corrects
  132. ** the extreme case when the initial value is LUA_MININTEGER, in which
  133. ** case the LUA_MININTEGER limit would still run the loop once.
  134. */
  135. static int forlimit (const TValue *obj, lua_Integer *p, lua_Integer step,
  136.                      int *stopnow) {
  137.   *stopnow = 0;  /* usually, let loops run */
  138.   if (!luaV_tointeger(obj, p, (step < 0 ? 2 : 1))) {  /* not fit in integer? */
  139.     lua_Number n;  /* try to convert to float */
  140.     if (!tonumber(obj, &n)) /* cannot convert to float? */
  141.       return 0;  /* not a number */
  142.     if (luai_numlt(0, n)) {  /* if true, float is larger than max integer */
  143.       *p = LUA_MAXINTEGER;
  144.       if (step < 0) *stopnow = 1;
  145.     }
  146.     else {  /* float is smaller than min integer */
  147.       *p = LUA_MININTEGER;
  148.       if (step >= 0) *stopnow = 1;
  149.     }
  150.   }
  151.   return 1;
  152. }
  153.  
  154.  
  155. /*
  156. ** Finish the table access 'val = t[key]'.
  157. ** if 'slot' is NULL, 't' is not a table; otherwise, 'slot' points to
  158. ** t[k] entry (which must be nil).
  159. */
  160. void luaV_finishget (lua_State *L, const TValue *t, TValue *key, StkId val,
  161.                       const TValue *slot) {
  162.   int loop;  /* counter to avoid infinite loops */
  163.   const TValue *tm;  /* metamethod */
  164.   for (loop = 0; loop < MAXTAGLOOP; loop++) {
  165.     if (slot == NULL) {  /* 't' is not a table? */
  166.       lua_assert(!ttistable(t));
  167.       tm = luaT_gettmbyobj(L, t, TM_INDEX);
  168.       if (ttisnil(tm))
  169.         luaG_typeerror(L, t, "index");  /* no metamethod */
  170.       /* else will try the metamethod */
  171.     }
  172.     else {  /* 't' is a table */
  173.       lua_assert(ttisnil(slot));
  174.       tm = fasttm(L, hvalue(t)->metatable, TM_INDEX);  /* table's metamethod */
  175.       if (tm == NULL) {  /* no metamethod? */
  176.         setnilvalue(val);  /* result is nil */
  177.         return;
  178.       }
  179.       /* else will try the metamethod */
  180.     }
  181.     if (ttisfunction(tm)) {  /* is metamethod a function? */
  182.       luaT_callTM(L, tm, t, key, val, 1);  /* call it */
  183.       return;
  184.     }
  185.     t = tm;  /* else try to access 'tm[key]' */
  186.     if (luaV_fastget(L,t,key,slot,luaH_get)) {  /* fast track? */
  187.       setobj2s(L, val, slot);  /* done */
  188.       return;
  189.     }
  190.     /* else repeat (tail call 'luaV_finishget') */
  191.   }
  192.   luaG_runerror(L, "'__index' chain too long; possible loop");
  193. }
  194.  
  195.  
  196. /*
  197. ** Finish a table assignment 't[key] = val'.
  198. ** If 'slot' is NULL, 't' is not a table.  Otherwise, 'slot' points
  199. ** to the entry 't[key]', or to 'luaO_nilobject' if there is no such
  200. ** entry.  (The value at 'slot' must be nil, otherwise 'luaV_fastset'
  201. ** would have done the job.)
  202. */
  203. void luaV_finishset (lua_State *L, const TValue *t, TValue *key,
  204.                      StkId val, const TValue *slot) {
  205.   int loop;  /* counter to avoid infinite loops */
  206.   for (loop = 0; loop < MAXTAGLOOP; loop++) {
  207.     const TValue *tm;  /* '__newindex' metamethod */
  208.     if (slot != NULL) {  /* is 't' a table? */
  209.       Table *h = hvalue(t);  /* save 't' table */
  210.       lua_assert(ttisnil(slot));  /* old value must be nil */
  211.       tm = fasttm(L, h->metatable, TM_NEWINDEX);  /* get metamethod */
  212.       if (tm == NULL) {  /* no metamethod? */
  213.         if (slot == luaO_nilobject)  /* no previous entry? */
  214.           slot = luaH_newkey(L, h, key);  /* create one */
  215.         /* no metamethod and (now) there is an entry with given key */
  216.         setobj2t(L, cast(TValue *, slot), val);  /* set its new value */
  217.         invalidateTMcache(h);
  218.         luaC_barrierback(L, h, val);
  219.         return;
  220.       }
  221.       /* else will try the metamethod */
  222.     }
  223.     else {  /* not a table; check metamethod */
  224.       if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))
  225.         luaG_typeerror(L, t, "index");
  226.     }
  227.     /* try the metamethod */
  228.     if (ttisfunction(tm)) {
  229.       luaT_callTM(L, tm, t, key, val, 0);
  230.       return;
  231.     }
  232.     t = tm;  /* else repeat assignment over 'tm' */
  233.     if (luaV_fastset(L, t, key, slot, luaH_get, val))
  234.       return;  /* done */
  235.     /* else loop */
  236.   }
  237.   luaG_runerror(L, "'__newindex' chain too long; possible loop");
  238. }
  239.  
  240.  
  241. /*
  242. ** Compare two strings 'ls' x 'rs', returning an integer smaller-equal-
  243. ** -larger than zero if 'ls' is smaller-equal-larger than 'rs'.
  244. ** The code is a little tricky because it allows '\0' in the strings
  245. ** and it uses 'strcoll' (to respect locales) for each segments
  246. ** of the strings.
  247. */
  248. static int l_strcmp (const TString *ls, const TString *rs) {
  249.   const char *l = getstr(ls);
  250.   size_t ll = tsslen(ls);
  251.   const char *r = getstr(rs);
  252.   size_t lr = tsslen(rs);
  253.   for (;;) {  /* for each segment */
  254.     int temp = strcoll(l, r);
  255.     if (temp != 0)  /* not equal? */
  256.       return temp;  /* done */
  257.     else {  /* strings are equal up to a '\0' */
  258.       size_t len = strlen(l);  /* index of first '\0' in both strings */
  259.       if (len == lr)  /* 'rs' is finished? */
  260.         return (len == ll) ? 0 : 1;  /* check 'ls' */
  261.       else if (len == ll)  /* 'ls' is finished? */
  262.         return -1;  /* 'ls' is smaller than 'rs' ('rs' is not finished) */
  263.       /* both strings longer than 'len'; go on comparing after the '\0' */
  264.       len++;
  265.       l += len; ll -= len; r += len; lr -= len;
  266.     }
  267.   }
  268. }
  269.  
  270.  
  271. /*
  272. ** Check whether integer 'i' is less than float 'f'. If 'i' has an
  273. ** exact representation as a float ('l_intfitsf'), compare numbers as
  274. ** floats. Otherwise, if 'f' is outside the range for integers, result
  275. ** is trivial. Otherwise, compare them as integers. (When 'i' has no
  276. ** float representation, either 'f' is "far away" from 'i' or 'f' has
  277. ** no precision left for a fractional part; either way, how 'f' is
  278. ** truncated is irrelevant.) When 'f' is NaN, comparisons must result
  279. ** in false.
  280. */
  281. static int LTintfloat (lua_Integer i, lua_Number f) {
  282. #if defined(l_intfitsf)
  283.   if (!l_intfitsf(i)) {
  284.     if (f >= -cast_num(LUA_MININTEGER))  /* -minint == maxint + 1 */
  285.       return 1;  /* f >= maxint + 1 > i */
  286.     else if (f > cast_num(LUA_MININTEGER))  /* minint < f <= maxint ? */
  287.       return (i < cast(lua_Integer, f));  /* compare them as integers */
  288.     else  /* f <= minint <= i (or 'f' is NaN)  -->  not(i < f) */
  289.       return 0;
  290.   }
  291. #endif
  292.   return luai_numlt(cast_num(i), f);  /* compare them as floats */
  293. }
  294.  
  295.  
  296. /*
  297. ** Check whether integer 'i' is less than or equal to float 'f'.
  298. ** See comments on previous function.
  299. */
  300. static int LEintfloat (lua_Integer i, lua_Number f) {
  301. #if defined(l_intfitsf)
  302.   if (!l_intfitsf(i)) {
  303.     if (f >= -cast_num(LUA_MININTEGER))  /* -minint == maxint + 1 */
  304.       return 1;  /* f >= maxint + 1 > i */
  305.     else if (f >= cast_num(LUA_MININTEGER))  /* minint <= f <= maxint ? */
  306.       return (i <= cast(lua_Integer, f));  /* compare them as integers */
  307.     else  /* f < minint <= i (or 'f' is NaN)  -->  not(i <= f) */
  308.       return 0;
  309.   }
  310. #endif
  311.   return luai_numle(cast_num(i), f);  /* compare them as floats */
  312. }
  313.  
  314.  
  315. /*
  316. ** Return 'l < r', for numbers.
  317. */
  318. static int LTnum (const TValue *l, const TValue *r) {
  319.   if (ttisinteger(l)) {
  320.     lua_Integer li = ivalue(l);
  321.     if (ttisinteger(r))
  322.       return li < ivalue(r);  /* both are integers */
  323.     else  /* 'l' is int and 'r' is float */
  324.       return LTintfloat(li, fltvalue(r));  /* l < r ? */
  325.   }
  326.   else {
  327.     lua_Number lf = fltvalue(l);  /* 'l' must be float */
  328.     if (ttisfloat(r))
  329.       return luai_numlt(lf, fltvalue(r));  /* both are float */
  330.     else if (luai_numisnan(lf))  /* 'r' is int and 'l' is float */
  331.       return 0;  /* NaN < i is always false */
  332.     else  /* without NaN, (l < r)  <-->  not(r <= l) */
  333.       return !LEintfloat(ivalue(r), lf);  /* not (r <= l) ? */
  334.   }
  335. }
  336.  
  337.  
  338. /*
  339. ** Return 'l <= r', for numbers.
  340. */
  341. static int LEnum (const TValue *l, const TValue *r) {
  342.   if (ttisinteger(l)) {
  343.     lua_Integer li = ivalue(l);
  344.     if (ttisinteger(r))
  345.       return li <= ivalue(r);  /* both are integers */
  346.     else  /* 'l' is int and 'r' is float */
  347.       return LEintfloat(li, fltvalue(r));  /* l <= r ? */
  348.   }
  349.   else {
  350.     lua_Number lf = fltvalue(l);  /* 'l' must be float */
  351.     if (ttisfloat(r))
  352.       return luai_numle(lf, fltvalue(r));  /* both are float */
  353.     else if (luai_numisnan(lf))  /* 'r' is int and 'l' is float */
  354.       return 0;  /*  NaN <= i is always false */
  355.     else  /* without NaN, (l <= r)  <-->  not(r < l) */
  356.       return !LTintfloat(ivalue(r), lf);  /* not (r < l) ? */
  357.   }
  358. }
  359.  
  360.  
  361. /*
  362. ** Main operation less than; return 'l < r'.
  363. */
  364. int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r) {
  365.   int res;
  366.   if (ttisnumber(l) && ttisnumber(r))  /* both operands are numbers? */
  367.     return LTnum(l, r);
  368.   else if (ttisstring(l) && ttisstring(r))  /* both are strings? */
  369.     return l_strcmp(tsvalue(l), tsvalue(r)) < 0;
  370.   else if ((res = luaT_callorderTM(L, l, r, TM_LT)) < 0)  /* no metamethod? */
  371.     luaG_ordererror(L, l, r);  /* error */
  372.   return res;
  373. }
  374.  
  375.  
  376. /*
  377. ** Main operation less than or equal to; return 'l <= r'. If it needs
  378. ** a metamethod and there is no '__le', try '__lt', based on
  379. ** l <= r iff !(r < l) (assuming a total order). If the metamethod
  380. ** yields during this substitution, the continuation has to know
  381. ** about it (to negate the result of r<l); bit CIST_LEQ in the call
  382. ** status keeps that information.
  383. */
  384. int luaV_lessequal (lua_State *L, const TValue *l, const TValue *r) {
  385.   int res;
  386.   if (ttisnumber(l) && ttisnumber(r))  /* both operands are numbers? */
  387.     return LEnum(l, r);
  388.   else if (ttisstring(l) && ttisstring(r))  /* both are strings? */
  389.     return l_strcmp(tsvalue(l), tsvalue(r)) <= 0;
  390.   else if ((res = luaT_callorderTM(L, l, r, TM_LE)) >= 0)  /* try 'le' */
  391.     return res;
  392.   else {  /* try 'lt': */
  393.     L->ci->callstatus |= CIST_LEQ;  /* mark it is doing 'lt' for 'le' */
  394.     res = luaT_callorderTM(L, r, l, TM_LT);
  395.     L->ci->callstatus ^= CIST_LEQ;  /* clear mark */
  396.     if (res < 0)
  397.       luaG_ordererror(L, l, r);
  398.     return !res;  /* result is negated */
  399.   }
  400. }
  401.  
  402.  
  403. /*
  404. ** Main operation for equality of Lua values; return 't1 == t2'.
  405. ** L == NULL means raw equality (no metamethods)
  406. */
  407. int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2) {
  408.   const TValue *tm;
  409.   if (ttype(t1) != ttype(t2)) {  /* not the same variant? */
  410.     if (ttnov(t1) != ttnov(t2) || ttnov(t1) != LUA_TNUMBER)
  411.       return 0;  /* only numbers can be equal with different variants */
  412.     else {  /* two numbers with different variants */
  413.       lua_Integer i1, i2;  /* compare them as integers */
  414.       return (tointeger(t1, &i1) && tointeger(t2, &i2) && i1 == i2);
  415.     }
  416.   }
  417.   /* values have same type and same variant */
  418.   switch (ttype(t1)) {
  419.     case LUA_TNIL: return 1;
  420.     case LUA_TNUMINT: return (ivalue(t1) == ivalue(t2));
  421.     case LUA_TNUMFLT: return luai_numeq(fltvalue(t1), fltvalue(t2));
  422.     case LUA_TBOOLEAN: return bvalue(t1) == bvalue(t2);  /* true must be 1 !! */
  423.     case LUA_TLIGHTUSERDATA: return pvalue(t1) == pvalue(t2);
  424.     case LUA_TLCF: return fvalue(t1) == fvalue(t2);
  425.     case LUA_TSHRSTR: return eqshrstr(tsvalue(t1), tsvalue(t2));
  426.     case LUA_TLNGSTR: return luaS_eqlngstr(tsvalue(t1), tsvalue(t2));
  427.     case LUA_TUSERDATA: {
  428.       if (uvalue(t1) == uvalue(t2)) return 1;
  429.       else if (L == NULL) return 0;
  430.       tm = fasttm(L, uvalue(t1)->metatable, TM_EQ);
  431.       if (tm == NULL)
  432.         tm = fasttm(L, uvalue(t2)->metatable, TM_EQ);
  433.       break;  /* will try TM */
  434.     }
  435.     case LUA_TTABLE: {
  436.       if (hvalue(t1) == hvalue(t2)) return 1;
  437.       else if (L == NULL) return 0;
  438.       tm = fasttm(L, hvalue(t1)->metatable, TM_EQ);
  439.       if (tm == NULL)
  440.         tm = fasttm(L, hvalue(t2)->metatable, TM_EQ);
  441.       break;  /* will try TM */
  442.     }
  443.     default:
  444.       return gcvalue(t1) == gcvalue(t2);
  445.   }
  446.   if (tm == NULL)  /* no TM? */
  447.     return 0;  /* objects are different */
  448.   luaT_callTM(L, tm, t1, t2, L->top, 1);  /* call TM */
  449.   return !l_isfalse(L->top);
  450. }
  451.  
  452.  
  453. /* macro used by 'luaV_concat' to ensure that element at 'o' is a string */
  454. #define tostring(L,o)  \
  455.         (ttisstring(o) || (cvt2str(o) && (luaO_tostring(L, o), 1)))
  456.  
  457. #define isemptystr(o)   (ttisshrstring(o) && tsvalue(o)->shrlen == 0)
  458.  
  459. /* copy strings in stack from top - n up to top - 1 to buffer */
  460. static void copy2buff (StkId top, int n, char *buff) {
  461.   size_t tl = 0;  /* size already copied */
  462.   do {
  463.     size_t l = vslen(top - n);  /* length of string being copied */
  464.     memcpy(buff + tl, svalue(top - n), l * sizeof(char));
  465.     tl += l;
  466.   } while (--n > 0);
  467. }
  468.  
  469.  
  470. /*
  471. ** Main operation for concatenation: concat 'total' values in the stack,
  472. ** from 'L->top - total' up to 'L->top - 1'.
  473. */
  474. void luaV_concat (lua_State *L, int total) {
  475.   lua_assert(total >= 2);
  476.   do {
  477.     StkId top = L->top;
  478.     int n = 2;  /* number of elements handled in this pass (at least 2) */
  479.     if (!(ttisstring(top-2) || cvt2str(top-2)) || !tostring(L, top-1))
  480.       luaT_trybinTM(L, top-2, top-1, top-2, TM_CONCAT);
  481.     else if (isemptystr(top - 1))  /* second operand is empty? */
  482.       cast_void(tostring(L, top - 2));  /* result is first operand */
  483.     else if (isemptystr(top - 2)) {  /* first operand is an empty string? */
  484.       setobjs2s(L, top - 2, top - 1);  /* result is second op. */
  485.     }
  486.     else {
  487.       /* at least two non-empty string values; get as many as possible */
  488.       size_t tl = vslen(top - 1);
  489.       TString *ts;
  490.       /* collect total length and number of strings */
  491.       for (n = 1; n < total && tostring(L, top - n - 1); n++) {
  492.         size_t l = vslen(top - n - 1);
  493.         if (l >= (MAX_SIZE/sizeof(char)) - tl)
  494.           luaG_runerror(L, "string length overflow");
  495.         tl += l;
  496.       }
  497.       if (tl <= LUAI_MAXSHORTLEN) {  /* is result a short string? */
  498.         char buff[LUAI_MAXSHORTLEN];
  499.         copy2buff(top, n, buff);  /* copy strings to buffer */
  500.         ts = luaS_newlstr(L, buff, tl);
  501.       }
  502.       else {  /* long string; copy strings directly to final result */
  503.         ts = luaS_createlngstrobj(L, tl);
  504.         copy2buff(top, n, getstr(ts));
  505.       }
  506.       setsvalue2s(L, top - n, ts);  /* create result */
  507.     }
  508.     total -= n-1;  /* got 'n' strings to create 1 new */
  509.     L->top -= n-1;  /* popped 'n' strings and pushed one */
  510.   } while (total > 1);  /* repeat until only 1 result left */
  511. }
  512.  
  513.  
  514. /*
  515. ** Main operation 'ra' = #rb'.
  516. */
  517. void luaV_objlen (lua_State *L, StkId ra, const TValue *rb) {
  518.   const TValue *tm;
  519.   switch (ttype(rb)) {
  520.     case LUA_TTABLE: {
  521.       Table *h = hvalue(rb);
  522.       tm = fasttm(L, h->metatable, TM_LEN);
  523.       if (tm) break;  /* metamethod? break switch to call it */
  524.       setivalue(ra, luaH_getn(h));  /* else primitive len */
  525.       return;
  526.     }
  527.     case LUA_TSHRSTR: {
  528.       setivalue(ra, tsvalue(rb)->shrlen);
  529.       return;
  530.     }
  531.     case LUA_TLNGSTR: {
  532.       setivalue(ra, tsvalue(rb)->u.lnglen);
  533.       return;
  534.     }
  535.     default: {  /* try metamethod */
  536.       tm = luaT_gettmbyobj(L, rb, TM_LEN);
  537.       if (ttisnil(tm))  /* no metamethod? */
  538.         luaG_typeerror(L, rb, "get length of");
  539.       break;
  540.     }
  541.   }
  542.   luaT_callTM(L, tm, rb, rb, ra, 1);
  543. }
  544.  
  545.  
  546. /*
  547. ** Integer division; return 'm // n', that is, floor(m/n).
  548. ** C division truncates its result (rounds towards zero).
  549. ** 'floor(q) == trunc(q)' when 'q >= 0' or when 'q' is integer,
  550. ** otherwise 'floor(q) == trunc(q) - 1'.
  551. */
  552. lua_Integer luaV_div (lua_State *L, lua_Integer m, lua_Integer n) {
  553.   if (l_castS2U(n) + 1u <= 1u) {  /* special cases: -1 or 0 */
  554.     if (n == 0)
  555.       luaG_runerror(L, "attempt to divide by zero");
  556.     return intop(-, 0, m);   /* n==-1; avoid overflow with 0x80000...//-1 */
  557.   }
  558.   else {
  559.     lua_Integer q = m / n;  /* perform C division */
  560.     if ((m ^ n) < 0 && m % n != 0)  /* 'm/n' would be negative non-integer? */
  561.       q -= 1;  /* correct result for different rounding */
  562.     return q;
  563.   }
  564. }
  565.  
  566.  
  567. /*
  568. ** Integer modulus; return 'm % n'. (Assume that C '%' with
  569. ** negative operands follows C99 behavior. See previous comment
  570. ** about luaV_div.)
  571. */
  572. lua_Integer luaV_mod (lua_State *L, lua_Integer m, lua_Integer n) {
  573.   if (l_castS2U(n) + 1u <= 1u) {  /* special cases: -1 or 0 */
  574.     if (n == 0)
  575.       luaG_runerror(L, "attempt to perform 'n%%0'");
  576.     return 0;   /* m % -1 == 0; avoid overflow with 0x80000...%-1 */
  577.   }
  578.   else {
  579.     lua_Integer r = m % n;
  580.     if (r != 0 && (m ^ n) < 0)  /* 'm/n' would be non-integer negative? */
  581.       r += n;  /* correct result for different rounding */
  582.     return r;
  583.   }
  584. }
  585.  
  586.  
  587. /* number of bits in an integer */
  588. #define NBITS   cast_int(sizeof(lua_Integer) * CHAR_BIT)
  589.  
  590. /*
  591. ** Shift left operation. (Shift right just negates 'y'.)
  592. */
  593. lua_Integer luaV_shiftl (lua_Integer x, lua_Integer y) {
  594.   if (y < 0) {  /* shift right? */
  595.     if (y <= -NBITS) return 0;
  596.     else return intop(>>, x, -y);
  597.   }
  598.   else {  /* shift left */
  599.     if (y >= NBITS) return 0;
  600.     else return intop(<<, x, y);
  601.   }
  602. }
  603.  
  604.  
  605. /*
  606. ** check whether cached closure in prototype 'p' may be reused, that is,
  607. ** whether there is a cached closure with the same upvalues needed by
  608. ** new closure to be created.
  609. */
  610. static LClosure *getcached (Proto *p, UpVal **encup, StkId base) {
  611.   LClosure *c = p->cache;
  612.   if (c != NULL) {  /* is there a cached closure? */
  613.     int nup = p->sizeupvalues;
  614.     Upvaldesc *uv = p->upvalues;
  615.     int i;
  616.     for (i = 0; i < nup; i++) {  /* check whether it has right upvalues */
  617.       TValue *v = uv[i].instack ? base + uv[i].idx : encup[uv[i].idx]->v;
  618.       if (c->upvals[i]->v != v)
  619.         return NULL;  /* wrong upvalue; cannot reuse closure */
  620.     }
  621.   }
  622.   return c;  /* return cached closure (or NULL if no cached closure) */
  623. }
  624.  
  625.  
  626. /*
  627. ** create a new Lua closure, push it in the stack, and initialize
  628. ** its upvalues. Note that the closure is not cached if prototype is
  629. ** already black (which means that 'cache' was already cleared by the
  630. ** GC).
  631. */
  632. static void pushclosure (lua_State *L, Proto *p, UpVal **encup, StkId base,
  633.                          StkId ra) {
  634.   int nup = p->sizeupvalues;
  635.   Upvaldesc *uv = p->upvalues;
  636.   int i;
  637.   LClosure *ncl = luaF_newLclosure(L, nup);
  638.   ncl->p = p;
  639.   setclLvalue(L, ra, ncl);  /* anchor new closure in stack */
  640.   for (i = 0; i < nup; i++) {  /* fill in its upvalues */
  641.     if (uv[i].instack)  /* upvalue refers to local variable? */
  642.       ncl->upvals[i] = luaF_findupval(L, base + uv[i].idx);
  643.     else  /* get upvalue from enclosing function */
  644.       ncl->upvals[i] = encup[uv[i].idx];
  645.     ncl->upvals[i]->refcount++;
  646.     /* new closure is white, so we do not need a barrier here */
  647.   }
  648.   if (!isblack(p))  /* cache will not break GC invariant? */
  649.     p->cache = ncl;  /* save it on cache for reuse */
  650. }
  651.  
  652.  
  653. /*
  654. ** finish execution of an opcode interrupted by an yield
  655. */
  656. void luaV_finishOp (lua_State *L) {
  657.   CallInfo *ci = L->ci;
  658.   StkId base = ci->u.l.base;
  659.   Instruction inst = *(ci->u.l.savedpc - 1);  /* interrupted instruction */
  660.   OpCode op = GET_OPCODE(inst);
  661.   switch (op) {  /* finish its execution */
  662.     case OP_ADD: case OP_SUB: case OP_MUL: case OP_DIV: case OP_IDIV:
  663.     case OP_BAND: case OP_BOR: case OP_BXOR: case OP_SHL: case OP_SHR:
  664.     case OP_MOD: case OP_POW:
  665.     case OP_UNM: case OP_BNOT: case OP_LEN:
  666.     case OP_GETTABUP: case OP_GETTABLE: case OP_SELF: {
  667.       setobjs2s(L, base + GETARG_A(inst), --L->top);
  668.       break;
  669.     }
  670.     case OP_LE: case OP_LT: case OP_EQ: {
  671.       int res = !l_isfalse(L->top - 1);
  672.       L->top--;
  673.       if (ci->callstatus & CIST_LEQ) {  /* "<=" using "<" instead? */
  674.         lua_assert(op == OP_LE);
  675.         ci->callstatus ^= CIST_LEQ;  /* clear mark */
  676.         res = !res;  /* negate result */
  677.       }
  678.       lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_JMP);
  679.       if (res != GETARG_A(inst))  /* condition failed? */
  680.         ci->u.l.savedpc++;  /* skip jump instruction */
  681.       break;
  682.     }
  683.     case OP_CONCAT: {
  684.       StkId top = L->top - 1;  /* top when 'luaT_trybinTM' was called */
  685.       int b = GETARG_B(inst);      /* first element to concatenate */
  686.       int total = cast_int(top - 1 - (base + b));  /* yet to concatenate */
  687.       setobj2s(L, top - 2, top);  /* put TM result in proper position */
  688.       if (total > 1) {  /* are there elements to concat? */
  689.         L->top = top - 1;  /* top is one after last element (at top-2) */
  690.         luaV_concat(L, total);  /* concat them (may yield again) */
  691.       }
  692.       /* move final result to final position */
  693.       setobj2s(L, ci->u.l.base + GETARG_A(inst), L->top - 1);
  694.       L->top = ci->top;  /* restore top */
  695.       break;
  696.     }
  697.     case OP_TFORCALL: {
  698.       lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_TFORLOOP);
  699.       L->top = ci->top;  /* correct top */
  700.       break;
  701.     }
  702.     case OP_CALL: {
  703.       if (GETARG_C(inst) - 1 >= 0)  /* nresults >= 0? */
  704.         L->top = ci->top;  /* adjust results */
  705.       break;
  706.     }
  707.     case OP_TAILCALL: case OP_SETTABUP: case OP_SETTABLE:
  708.       break;
  709.     default: lua_assert(0);
  710.   }
  711. }
  712.  
  713.  
  714.  
  715.  
  716. /*
  717. ** {==================================================================
  718. ** Function 'luaV_execute': main interpreter loop
  719. ** ===================================================================
  720. */
  721.  
  722.  
  723. /*
  724. ** some macros for common tasks in 'luaV_execute'
  725. */
  726.  
  727.  
  728. #define RA(i)   (base+GETARG_A(i))
  729. #define RB(i)   check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_B(i))
  730. #define RC(i)   check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))
  731. #define RKB(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, \
  732.         ISK(GETARG_B(i)) ? k+INDEXK(GETARG_B(i)) : base+GETARG_B(i))
  733. #define RKC(i)  check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \
  734.         ISK(GETARG_C(i)) ? k+INDEXK(GETARG_C(i)) : base+GETARG_C(i))
  735.  
  736.  
  737. /* execute a jump instruction */
  738. #define dojump(ci,i,e) \
  739.   { int a = GETARG_A(i); \
  740.     if (a != 0) luaF_close(L, ci->u.l.base + a - 1); \
  741.     ci->u.l.savedpc += GETARG_sBx(i) + e; }
  742.  
  743. /* for test instructions, execute the jump instruction that follows it */
  744. #define donextjump(ci)  { i = *ci->u.l.savedpc; dojump(ci, i, 1); }
  745.  
  746.  
  747. #define Protect(x)      { {x;}; base = ci->u.l.base; }
  748.  
  749. #define checkGC(L,c)  \
  750.         { luaC_condGC(L, L->top = (c),  /* limit of live values */ \
  751.                          Protect(L->top = ci->top));  /* restore top */ \
  752.            luai_threadyield(L); }
  753.  
  754.  
  755. /* fetch an instruction and prepare its execution */
  756. #define vmfetch()       { \
  757.   i = *(ci->u.l.savedpc++); \
  758.   if (L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) \
  759.     Protect(luaG_traceexec(L)); \
  760.   ra = RA(i); /* WARNING: any stack reallocation invalidates 'ra' */ \
  761.   lua_assert(base == ci->u.l.base); \
  762.   lua_assert(base <= L->top && L->top < L->stack + L->stacksize); \
  763. }
  764.  
  765. #define vmdispatch(o)   switch(o)
  766. #define vmcase(l)       case l:
  767. #define vmbreak         break
  768.  
  769.  
  770. /*
  771. ** copy of 'luaV_gettable', but protecting the call to potential
  772. ** metamethod (which can reallocate the stack)
  773. */
  774. #define gettableProtected(L,t,k,v)  { const TValue *slot; \
  775.   if (luaV_fastget(L,t,k,slot,luaH_get)) { setobj2s(L, v, slot); } \
  776.   else Protect(luaV_finishget(L,t,k,v,slot)); }
  777.  
  778.  
  779. /* same for 'luaV_settable' */
  780. #define settableProtected(L,t,k,v) { const TValue *slot; \
  781.   if (!luaV_fastset(L,t,k,slot,luaH_get,v)) \
  782.     Protect(luaV_finishset(L,t,k,v,slot)); }
  783.  
  784.  
  785.  
  786. void luaV_execute (lua_State *L) {
  787.   CallInfo *ci = L->ci;
  788.   LClosure *cl;
  789.   TValue *k;
  790.   StkId base;
  791.   ci->callstatus |= CIST_FRESH;  /* fresh invocation of 'luaV_execute" */
  792.  newframe:  /* reentry point when frame changes (call/return) */
  793.   lua_assert(ci == L->ci);
  794.   cl = clLvalue(ci->func);  /* local reference to function's closure */
  795.   k = cl->p->k;  /* local reference to function's constant table */
  796.   base = ci->u.l.base;  /* local copy of function's base */
  797.   /* main loop of interpreter */
  798.   for (;;) {
  799.     Instruction i;
  800.     StkId ra;
  801.     vmfetch();
  802.     vmdispatch (GET_OPCODE(i)) {
  803.       vmcase(OP_MOVE) {
  804.         setobjs2s(L, ra, RB(i));
  805.         vmbreak;
  806.       }
  807.       vmcase(OP_LOADK) {
  808.         TValue *rb = k + GETARG_Bx(i);
  809.         setobj2s(L, ra, rb);
  810.         vmbreak;
  811.       }
  812.       vmcase(OP_LOADKX) {
  813.         TValue *rb;
  814.         lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_EXTRAARG);
  815.         rb = k + GETARG_Ax(*ci->u.l.savedpc++);
  816.         setobj2s(L, ra, rb);
  817.         vmbreak;
  818.       }
  819.       vmcase(OP_LOADBOOL) {
  820.         setbvalue(ra, GETARG_B(i));
  821.         if (GETARG_C(i)) ci->u.l.savedpc++;  /* skip next instruction (if C) */
  822.         vmbreak;
  823.       }
  824.       vmcase(OP_LOADNIL) {
  825.         int b = GETARG_B(i);
  826.         do {
  827.           setnilvalue(ra++);
  828.         } while (b--);
  829.         vmbreak;
  830.       }
  831.       vmcase(OP_GETUPVAL) {
  832.         int b = GETARG_B(i);
  833.         setobj2s(L, ra, cl->upvals[b]->v);
  834.         vmbreak;
  835.       }
  836.       vmcase(OP_GETTABUP) {
  837.         TValue *upval = cl->upvals[GETARG_B(i)]->v;
  838.         TValue *rc = RKC(i);
  839.         gettableProtected(L, upval, rc, ra);
  840.         vmbreak;
  841.       }
  842.       vmcase(OP_GETTABLE) {
  843.         StkId rb = RB(i);
  844.         TValue *rc = RKC(i);
  845.         gettableProtected(L, rb, rc, ra);
  846.         vmbreak;
  847.       }
  848.       vmcase(OP_SETTABUP) {
  849.         TValue *upval = cl->upvals[GETARG_A(i)]->v;
  850.         TValue *rb = RKB(i);
  851.         TValue *rc = RKC(i);
  852.         settableProtected(L, upval, rb, rc);
  853.         vmbreak;
  854.       }
  855.       vmcase(OP_SETUPVAL) {
  856.         UpVal *uv = cl->upvals[GETARG_B(i)];
  857.         setobj(L, uv->v, ra);
  858.         luaC_upvalbarrier(L, uv);
  859.         vmbreak;
  860.       }
  861.       vmcase(OP_SETTABLE) {
  862.         TValue *rb = RKB(i);
  863.         TValue *rc = RKC(i);
  864.         settableProtected(L, ra, rb, rc);
  865.         vmbreak;
  866.       }
  867.       vmcase(OP_NEWTABLE) {
  868.         int b = GETARG_B(i);
  869.         int c = GETARG_C(i);
  870.         Table *t = luaH_new(L);
  871.         sethvalue(L, ra, t);
  872.         if (b != 0 || c != 0)
  873.           luaH_resize(L, t, luaO_fb2int(b), luaO_fb2int(c));
  874.         checkGC(L, ra + 1);
  875.         vmbreak;
  876.       }
  877.       vmcase(OP_SELF) {
  878.         const TValue *aux;
  879.         StkId rb = RB(i);
  880.         TValue *rc = RKC(i);
  881.         TString *key = tsvalue(rc);  /* key must be a string */
  882.         setobjs2s(L, ra + 1, rb);
  883.         if (luaV_fastget(L, rb, key, aux, luaH_getstr)) {
  884.           setobj2s(L, ra, aux);
  885.         }
  886.         else Protect(luaV_finishget(L, rb, rc, ra, aux));
  887.         vmbreak;
  888.       }
  889.       vmcase(OP_ADD) {
  890.         TValue *rb = RKB(i);
  891.         TValue *rc = RKC(i);
  892.         lua_Number nb; lua_Number nc;
  893.         if (ttisinteger(rb) && ttisinteger(rc)) {
  894.           lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
  895.           setivalue(ra, intop(+, ib, ic));
  896.         }
  897.         else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
  898.           setfltvalue(ra, luai_numadd(L, nb, nc));
  899.         }
  900.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_ADD)); }
  901.         vmbreak;
  902.       }
  903.       vmcase(OP_SUB) {
  904.         TValue *rb = RKB(i);
  905.         TValue *rc = RKC(i);
  906.         lua_Number nb; lua_Number nc;
  907.         if (ttisinteger(rb) && ttisinteger(rc)) {
  908.           lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
  909.           setivalue(ra, intop(-, ib, ic));
  910.         }
  911.         else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
  912.           setfltvalue(ra, luai_numsub(L, nb, nc));
  913.         }
  914.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_SUB)); }
  915.         vmbreak;
  916.       }
  917.       vmcase(OP_MUL) {
  918.         TValue *rb = RKB(i);
  919.         TValue *rc = RKC(i);
  920.         lua_Number nb; lua_Number nc;
  921.         if (ttisinteger(rb) && ttisinteger(rc)) {
  922.           lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
  923.           setivalue(ra, intop(*, ib, ic));
  924.         }
  925.         else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
  926.           setfltvalue(ra, luai_nummul(L, nb, nc));
  927.         }
  928.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_MUL)); }
  929.         vmbreak;
  930.       }
  931.       vmcase(OP_DIV) {  /* float division (always with floats) */
  932.         TValue *rb = RKB(i);
  933.         TValue *rc = RKC(i);
  934.         lua_Number nb; lua_Number nc;
  935.         if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
  936.           setfltvalue(ra, luai_numdiv(L, nb, nc));
  937.         }
  938.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_DIV)); }
  939.         vmbreak;
  940.       }
  941.       vmcase(OP_BAND) {
  942.         TValue *rb = RKB(i);
  943.         TValue *rc = RKC(i);
  944.         lua_Integer ib; lua_Integer ic;
  945.         if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
  946.           setivalue(ra, intop(&, ib, ic));
  947.         }
  948.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_BAND)); }
  949.         vmbreak;
  950.       }
  951.       vmcase(OP_BOR) {
  952.         TValue *rb = RKB(i);
  953.         TValue *rc = RKC(i);
  954.         lua_Integer ib; lua_Integer ic;
  955.         if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
  956.           setivalue(ra, intop(|, ib, ic));
  957.         }
  958.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_BOR)); }
  959.         vmbreak;
  960.       }
  961.       vmcase(OP_BXOR) {
  962.         TValue *rb = RKB(i);
  963.         TValue *rc = RKC(i);
  964.         lua_Integer ib; lua_Integer ic;
  965.         if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
  966.           setivalue(ra, intop(^, ib, ic));
  967.         }
  968.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_BXOR)); }
  969.         vmbreak;
  970.       }
  971.       vmcase(OP_SHL) {
  972.         TValue *rb = RKB(i);
  973.         TValue *rc = RKC(i);
  974.         lua_Integer ib; lua_Integer ic;
  975.         if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
  976.           setivalue(ra, luaV_shiftl(ib, ic));
  977.         }
  978.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_SHL)); }
  979.         vmbreak;
  980.       }
  981.       vmcase(OP_SHR) {
  982.         TValue *rb = RKB(i);
  983.         TValue *rc = RKC(i);
  984.         lua_Integer ib; lua_Integer ic;
  985.         if (tointeger(rb, &ib) && tointeger(rc, &ic)) {
  986.           setivalue(ra, luaV_shiftl(ib, -ic));
  987.         }
  988.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_SHR)); }
  989.         vmbreak;
  990.       }
  991.       vmcase(OP_MOD) {
  992.         TValue *rb = RKB(i);
  993.         TValue *rc = RKC(i);
  994.         lua_Number nb; lua_Number nc;
  995.         if (ttisinteger(rb) && ttisinteger(rc)) {
  996.           lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
  997.           setivalue(ra, luaV_mod(L, ib, ic));
  998.         }
  999.         else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
  1000.           lua_Number m;
  1001.           luai_nummod(L, nb, nc, m);
  1002.           setfltvalue(ra, m);
  1003.         }
  1004.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_MOD)); }
  1005.         vmbreak;
  1006.       }
  1007.       vmcase(OP_IDIV) {  /* floor division */
  1008.         TValue *rb = RKB(i);
  1009.         TValue *rc = RKC(i);
  1010.         lua_Number nb; lua_Number nc;
  1011.         if (ttisinteger(rb) && ttisinteger(rc)) {
  1012.           lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
  1013.           setivalue(ra, luaV_div(L, ib, ic));
  1014.         }
  1015.         else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
  1016.           setfltvalue(ra, luai_numidiv(L, nb, nc));
  1017.         }
  1018.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_IDIV)); }
  1019.         vmbreak;
  1020.       }
  1021.       vmcase(OP_POW) {
  1022.         TValue *rb = RKB(i);
  1023.         TValue *rc = RKC(i);
  1024.         lua_Number nb; lua_Number nc;
  1025.         if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
  1026.           setfltvalue(ra, luai_numpow(L, nb, nc));
  1027.         }
  1028.         else { Protect(luaT_trybinTM(L, rb, rc, ra, TM_POW)); }
  1029.         vmbreak;
  1030.       }
  1031.       vmcase(OP_UNM) {
  1032.         TValue *rb = RB(i);
  1033.         lua_Number nb;
  1034.         if (ttisinteger(rb)) {
  1035.           lua_Integer ib = ivalue(rb);
  1036.           setivalue(ra, intop(-, 0, ib));
  1037.         }
  1038.         else if (tonumber(rb, &nb)) {
  1039.           setfltvalue(ra, luai_numunm(L, nb));
  1040.         }
  1041.         else {
  1042.           Protect(luaT_trybinTM(L, rb, rb, ra, TM_UNM));
  1043.         }
  1044.         vmbreak;
  1045.       }
  1046.       vmcase(OP_BNOT) {
  1047.         TValue *rb = RB(i);
  1048.         lua_Integer ib;
  1049.         if (tointeger(rb, &ib)) {
  1050.           setivalue(ra, intop(^, ~l_castS2U(0), ib));
  1051.         }
  1052.         else {
  1053.           Protect(luaT_trybinTM(L, rb, rb, ra, TM_BNOT));
  1054.         }
  1055.         vmbreak;
  1056.       }
  1057.       vmcase(OP_NOT) {
  1058.         TValue *rb = RB(i);
  1059.         int res = l_isfalse(rb);  /* next assignment may change this value */
  1060.         setbvalue(ra, res);
  1061.         vmbreak;
  1062.       }
  1063.       vmcase(OP_LEN) {
  1064.         Protect(luaV_objlen(L, ra, RB(i)));
  1065.         vmbreak;
  1066.       }
  1067.       vmcase(OP_CONCAT) {
  1068.         int b = GETARG_B(i);
  1069.         int c = GETARG_C(i);
  1070.         StkId rb;
  1071.         L->top = base + c + 1;  /* mark the end of concat operands */
  1072.         Protect(luaV_concat(L, c - b + 1));
  1073.         ra = RA(i);  /* 'luaV_concat' may invoke TMs and move the stack */
  1074.         rb = base + b;
  1075.         setobjs2s(L, ra, rb);
  1076.         checkGC(L, (ra >= rb ? ra + 1 : rb));
  1077.         L->top = ci->top;  /* restore top */
  1078.         vmbreak;
  1079.       }
  1080.       vmcase(OP_JMP) {
  1081.         dojump(ci, i, 0);
  1082.         vmbreak;
  1083.       }
  1084.       vmcase(OP_EQ) {
  1085.         TValue *rb = RKB(i);
  1086.         TValue *rc = RKC(i);
  1087.         Protect(
  1088.           if (luaV_equalobj(L, rb, rc) != GETARG_A(i))
  1089.             ci->u.l.savedpc++;
  1090.           else
  1091.             donextjump(ci);
  1092.         )
  1093.         vmbreak;
  1094.       }
  1095.       vmcase(OP_LT) {
  1096.         Protect(
  1097.           if (luaV_lessthan(L, RKB(i), RKC(i)) != GETARG_A(i))
  1098.             ci->u.l.savedpc++;
  1099.           else
  1100.             donextjump(ci);
  1101.         )
  1102.         vmbreak;
  1103.       }
  1104.       vmcase(OP_LE) {
  1105.         Protect(
  1106.           if (luaV_lessequal(L, RKB(i), RKC(i)) != GETARG_A(i))
  1107.             ci->u.l.savedpc++;
  1108.           else
  1109.             donextjump(ci);
  1110.         )
  1111.         vmbreak;
  1112.       }
  1113.       vmcase(OP_TEST) {
  1114.         if (GETARG_C(i) ? l_isfalse(ra) : !l_isfalse(ra))
  1115.             ci->u.l.savedpc++;
  1116.           else
  1117.           donextjump(ci);
  1118.         vmbreak;
  1119.       }
  1120.       vmcase(OP_TESTSET) {
  1121.         TValue *rb = RB(i);
  1122.         if (GETARG_C(i) ? l_isfalse(rb) : !l_isfalse(rb))
  1123.           ci->u.l.savedpc++;
  1124.         else {
  1125.           setobjs2s(L, ra, rb);
  1126.           donextjump(ci);
  1127.         }
  1128.         vmbreak;
  1129.       }
  1130.       vmcase(OP_CALL) {
  1131.         int b = GETARG_B(i);
  1132.         int nresults = GETARG_C(i) - 1;
  1133.         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
  1134.         if (luaD_precall(L, ra, nresults)) {  /* C function? */
  1135.           if (nresults >= 0)
  1136.             L->top = ci->top;  /* adjust results */
  1137.           Protect((void)0);  /* update 'base' */
  1138.         }
  1139.         else {  /* Lua function */
  1140.           ci = L->ci;
  1141.           goto newframe;  /* restart luaV_execute over new Lua function */
  1142.         }
  1143.         vmbreak;
  1144.       }
  1145.       vmcase(OP_TAILCALL) {
  1146.         int b = GETARG_B(i);
  1147.         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
  1148.         lua_assert(GETARG_C(i) - 1 == LUA_MULTRET);
  1149.         if (luaD_precall(L, ra, LUA_MULTRET)) {  /* C function? */
  1150.           Protect((void)0);  /* update 'base' */
  1151.         }
  1152.         else {
  1153.           /* tail call: put called frame (n) in place of caller one (o) */
  1154.           CallInfo *nci = L->ci;  /* called frame */
  1155.           CallInfo *oci = nci->previous;  /* caller frame */
  1156.           StkId nfunc = nci->func;  /* called function */
  1157.           StkId ofunc = oci->func;  /* caller function */
  1158.           /* last stack slot filled by 'precall' */
  1159.           StkId lim = nci->u.l.base + getproto(nfunc)->numparams;
  1160.           int aux;
  1161.           /* close all upvalues from previous call */
  1162.           if (cl->p->sizep > 0) luaF_close(L, oci->u.l.base);
  1163.           /* move new frame into old one */
  1164.           for (aux = 0; nfunc + aux < lim; aux++)
  1165.             setobjs2s(L, ofunc + aux, nfunc + aux);
  1166.           oci->u.l.base = ofunc + (nci->u.l.base - nfunc);  /* correct base */
  1167.           oci->top = L->top = ofunc + (L->top - nfunc);  /* correct top */
  1168.           oci->u.l.savedpc = nci->u.l.savedpc;
  1169.           oci->callstatus |= CIST_TAIL;  /* function was tail called */
  1170.           ci = L->ci = oci;  /* remove new frame */
  1171.           lua_assert(L->top == oci->u.l.base + getproto(ofunc)->maxstacksize);
  1172.           goto newframe;  /* restart luaV_execute over new Lua function */
  1173.         }
  1174.         vmbreak;
  1175.       }
  1176.       vmcase(OP_RETURN) {
  1177.         int b = GETARG_B(i);
  1178.         if (cl->p->sizep > 0) luaF_close(L, base);
  1179.         b = luaD_poscall(L, ci, ra, (b != 0 ? b - 1 : cast_int(L->top - ra)));
  1180.         if (ci->callstatus & CIST_FRESH)  /* local 'ci' still from callee */
  1181.           return;  /* external invocation: return */
  1182.         else {  /* invocation via reentry: continue execution */
  1183.           ci = L->ci;
  1184.           if (b) L->top = ci->top;
  1185.           lua_assert(isLua(ci));
  1186.           lua_assert(GET_OPCODE(*((ci)->u.l.savedpc - 1)) == OP_CALL);
  1187.           goto newframe;  /* restart luaV_execute over new Lua function */
  1188.         }
  1189.       }
  1190.       vmcase(OP_FORLOOP) {
  1191.         if (ttisinteger(ra)) {  /* integer loop? */
  1192.           lua_Integer step = ivalue(ra + 2);
  1193.           lua_Integer idx = intop(+, ivalue(ra), step); /* increment index */
  1194.           lua_Integer limit = ivalue(ra + 1);
  1195.           if ((0 < step) ? (idx <= limit) : (limit <= idx)) {
  1196.             ci->u.l.savedpc += GETARG_sBx(i);  /* jump back */
  1197.             chgivalue(ra, idx);  /* update internal index... */
  1198.             setivalue(ra + 3, idx);  /* ...and external index */
  1199.           }
  1200.         }
  1201.         else {  /* floating loop */
  1202.           lua_Number step = fltvalue(ra + 2);
  1203.           lua_Number idx = luai_numadd(L, fltvalue(ra), step); /* inc. index */
  1204.           lua_Number limit = fltvalue(ra + 1);
  1205.           if (luai_numlt(0, step) ? luai_numle(idx, limit)
  1206.                                   : luai_numle(limit, idx)) {
  1207.             ci->u.l.savedpc += GETARG_sBx(i);  /* jump back */
  1208.             chgfltvalue(ra, idx);  /* update internal index... */
  1209.             setfltvalue(ra + 3, idx);  /* ...and external index */
  1210.           }
  1211.         }
  1212.         vmbreak;
  1213.       }
  1214.       vmcase(OP_FORPREP) {
  1215.         TValue *init = ra;
  1216.         TValue *plimit = ra + 1;
  1217.         TValue *pstep = ra + 2;
  1218.         lua_Integer ilimit;
  1219.         int stopnow;
  1220.         if (ttisinteger(init) && ttisinteger(pstep) &&
  1221.             forlimit(plimit, &ilimit, ivalue(pstep), &stopnow)) {
  1222.           /* all values are integer */
  1223.           lua_Integer initv = (stopnow ? 0 : ivalue(init));
  1224.           setivalue(plimit, ilimit);
  1225.           setivalue(init, intop(-, initv, ivalue(pstep)));
  1226.         }
  1227.         else {  /* try making all values floats */
  1228.           lua_Number ninit; lua_Number nlimit; lua_Number nstep;
  1229.           if (!tonumber(plimit, &nlimit))
  1230.             luaG_runerror(L, "'for' limit must be a number");
  1231.           setfltvalue(plimit, nlimit);
  1232.           if (!tonumber(pstep, &nstep))
  1233.             luaG_runerror(L, "'for' step must be a number");
  1234.           setfltvalue(pstep, nstep);
  1235.           if (!tonumber(init, &ninit))
  1236.             luaG_runerror(L, "'for' initial value must be a number");
  1237.           setfltvalue(init, luai_numsub(L, ninit, nstep));
  1238.         }
  1239.         ci->u.l.savedpc += GETARG_sBx(i);
  1240.         vmbreak;
  1241.       }
  1242.       vmcase(OP_TFORCALL) {
  1243.         StkId cb = ra + 3;  /* call base */
  1244.         setobjs2s(L, cb+2, ra+2);
  1245.         setobjs2s(L, cb+1, ra+1);
  1246.         setobjs2s(L, cb, ra);
  1247.         L->top = cb + 3;  /* func. + 2 args (state and index) */
  1248.         Protect(luaD_call(L, cb, GETARG_C(i)));
  1249.         L->top = ci->top;
  1250.         i = *(ci->u.l.savedpc++);  /* go to next instruction */
  1251.         ra = RA(i);
  1252.         lua_assert(GET_OPCODE(i) == OP_TFORLOOP);
  1253.         goto l_tforloop;
  1254.       }
  1255.       vmcase(OP_TFORLOOP) {
  1256.         l_tforloop:
  1257.         if (!ttisnil(ra + 1)) {  /* continue loop? */
  1258.           setobjs2s(L, ra, ra + 1);  /* save control variable */
  1259.            ci->u.l.savedpc += GETARG_sBx(i);  /* jump back */
  1260.         }
  1261.         vmbreak;
  1262.       }
  1263.       vmcase(OP_SETLIST) {
  1264.         int n = GETARG_B(i);
  1265.         int c = GETARG_C(i);
  1266.         unsigned int last;
  1267.         Table *h;
  1268.         if (n == 0) n = cast_int(L->top - ra) - 1;
  1269.         if (c == 0) {
  1270.           lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_EXTRAARG);
  1271.           c = GETARG_Ax(*ci->u.l.savedpc++);
  1272.         }
  1273.         h = hvalue(ra);
  1274.         last = ((c-1)*LFIELDS_PER_FLUSH) + n;
  1275.         if (last > h->sizearray)  /* needs more space? */
  1276.           luaH_resizearray(L, h, last);  /* preallocate it at once */
  1277.         for (; n > 0; n--) {
  1278.           TValue *val = ra+n;
  1279.           luaH_setint(L, h, last--, val);
  1280.           luaC_barrierback(L, h, val);
  1281.         }
  1282.         L->top = ci->top;  /* correct top (in case of previous open call) */
  1283.         vmbreak;
  1284.       }
  1285.       vmcase(OP_CLOSURE) {
  1286.         Proto *p = cl->p->p[GETARG_Bx(i)];
  1287.         LClosure *ncl = getcached(p, cl->upvals, base);  /* cached closure */
  1288.         if (ncl == NULL)  /* no match? */
  1289.           pushclosure(L, p, cl->upvals, base, ra);  /* create a new one */
  1290.         else
  1291.           setclLvalue(L, ra, ncl);  /* push cashed closure */
  1292.         checkGC(L, ra + 1);
  1293.         vmbreak;
  1294.       }
  1295.       vmcase(OP_VARARG) {
  1296.         int b = GETARG_B(i) - 1;  /* required results */
  1297.         int j;
  1298.         int n = cast_int(base - ci->func) - cl->p->numparams - 1;
  1299.         if (n < 0)  /* less arguments than parameters? */
  1300.           n = 0;  /* no vararg arguments */
  1301.         if (b < 0) {  /* B == 0? */
  1302.           b = n;  /* get all var. arguments */
  1303.           Protect(luaD_checkstack(L, n));
  1304.           ra = RA(i);  /* previous call may change the stack */
  1305.           L->top = ra + n;
  1306.         }
  1307.         for (j = 0; j < b && j < n; j++)
  1308.           setobjs2s(L, ra + j, base - n + j);
  1309.         for (; j < b; j++)  /* complete required results with nil */
  1310.           setnilvalue(ra + j);
  1311.         vmbreak;
  1312.       }
  1313.       vmcase(OP_EXTRAARG) {
  1314.         lua_assert(0);
  1315.         vmbreak;
  1316.       }
  1317.     }
  1318.   }
  1319. }
  1320.  
  1321. /* }================================================================== */
  1322.  
  1323.